Xbox 360 can't connect to internet

[jwalhous]

Hi,
I've followed all the guides and tried UPNP and manual Nat rules but can't get any of our xbox 360's to connect to the internet.
When doing the internet test it connects to network ok but fails internet connection.
We also have an xbox one and this works fine so it's kind of weird.
If anyone has any ideas it would be appreciated.

Regards
Jamie